Heating pad



June 4, 1940. 3 N. H. MCCLEARY HEATING PAD Original Filed June 19,1939 7 2 Sheets-Sheet 1 rmmvm's r 2 Sheets-Sheet 2 INVENTOR ATTORNEY .5

Jul-1e 1940- I I N. H. M CLEARY HEATING PAD Original Filed June 19,1939

r 4 BY 7 Reissue-d June 4, 1940 J UNITED S ATES HEATING ran Nolen H. McCle'ar-y, Chicago, 111., assignor to Benjamin E. Lawrence, Chicago, Ill.

Original No. 2,185,692, dated January 2, 1940,86-

rial No. 279,876, June 19, 1939L Application for reissue March 4,1940, Serial No. 322,266

x 11 Claims.

My invention relates to heating pads. Heat has long been used for the relief of pain. In modern practice, its therapeutic value has increased rather than decreased. The constant improvement, fora score of years, or more, of the so-called electric heating pad has brought this device to the forefront in the heat therapy field. It has achieved this position despite recognized imperfections which those in the industry have sought to overcome.

A factor of considerable significance has been the control of heat. The usual practice has been to attach resistance wire, suitably covered, as with asbestos, to a supporting sheet-like member, such as suitably treated canvas, wovenasbestos fabric or the like. Current control means are employed, conventionally secured to the same support as the resistance'wire. Because of the necessity, .in most cases, of providing for the control of the heat at several temperatures, and the diihculties involved therein, several thermostatic elements are employed as a rule, sometimes with multiple wiring and with multiple leads thereto.

The efiect of this practice, for a number of years more or less conventional, is the presence within the pad of considerable hard or unyielding inclusions which make contact with the body,

I particularly when the patient is lying on the pad 30 or holding it to a tender part, such as the face,

either distasteful or painful. Those skilled inv the art have sought for remedies for this conditlon, such as decreasing the size of thermostats,

' changing the character of the wire, and the like, but principally in attempts to devise padding means which will not impair the delivery of heat to the outside. Requirements of the fire underwriters have been a limiting factor in development, and because of the character of the device, 40 approval of the underwriters laboratories is important from the standpoint of both the manufacturer and. user.

One direction which development has taken is in the use of textile padding. This must be placed within or on the outside of the imperiorate rubber envelope demanded-by iire underwriters specifications. No attempt in this direction has met with full success, because of the fire hazard introduced, .the i introduction of material which will fail because ofthe absorption of moisture, such as perspiration, the in'eflectivn'ess of the material supplied as a cushion, or the loss of heat which results. At times, allot these dis- 55 advantages may be encountered.

The principal object of my invention is to overcome the, problems outlined hereinabove.

Another object is the provision of an improved heating pad.

A further object is the provision of a heating pad so adequately cushioned that a patient may lie on it with comfort, but which nevertheless will respond to deliver heat substantially to the extent as a generally similar pad not similarly cushioned.

In carrying out my invention, I employ material normally deemed of high heatinsulating character, but so construct and employ such material that it has fully adequate cushioning ac tion and only very slight heat insulating action. l preferably employ the imperforate, relatively thin rubber envelope referred to hereinabove, and may employ suitably designed material of my invention either within or on the outside ofthis envelope. Maximum cushioning effect is obtained with both. Within the rubber envelope, I employ, in a preferred embodiment, a layer of sponge rubber, provided with a series of openings insu'flicient in character and number to materially decrease the cushioning character of the sponge rubber, but sufficient in total area to pass at least the major proportion of the heat generated by the heating element. Exteriorly of the rubber envelope, I preferably utilize an outside envelope of textile material, having spaced sections of piling. The piling is substantially vertical to a supporting body of cloth, and, while it has more cushioning action as a heavy pad fabric, it has very little resistance to the flow of heat waves. p

A preferred embodiment of the invention is shown in the accompanying drawings. Other objects and features of the invention will be described in the detailed description of this preferred embodiment.

In the drawings, I

Fig. 1 is a perspectiveyiew showing the complete heating pad;

Fig. 2 is a plan view, with portions broken to illustrate the relationship of the parts;

Fig. 3 is an enlarged cross sectional view taken on the line 3-4 of Fig. 1; 1

Fig. 4 is a perspective view of the outer envelope;

Fig. 5 is a perspective view of the rubber envelope, with the contents thereof removed; and

Fig. 6 is an exploded view indicating the relationship of the parts which are assembled within the rubber envelope of Fig. 5.

For convenience, reference will first be made to away ll; so that either side of the pea may be placed be explained, and the reasons for and 'heat'control assembly I0 is sandwiched between layers ll of perforated aerated elastic material, such as sponge rubber, and inserted in a rubber envelope l2. This rubber envelope is suitably but permanently closed, the cord conductor ll extending through the closed edge.- The rubber envelope and contents are inserted in the 'zlpper-fastened outer envelope I, the resulting assembled product being shown in Fig. l. The principal details of construction of the parts will advantages of the construction, used.

The member l0 may be conventional. It comprises a. sheet-like support I, to which resistance wire I1 is secured, as by stitching. The wire and support are properly selected so as to avoid burning. The wire may be suitably covered with asbestos, and the support may be either a suitable canvas fabric, or an asbestos fabric. Fig. 3 shows, in elevation, a thermostat Ill, and any suitable number may be used, depending upon the design of the electrical circuit emplbyed.

The layers ll 'are preferably sponge rubber, with regularly arranged holes or perforations i8 extending entirely therethrough. Preferably, a layer I l is provided on both sides of the member against the body. In a standard size of pad, these layers are suitably'one-quarter to threeeighths of an inch thick, and the total area of the holes is from one-third to one-half the total area of the layer. The design of the holes may vary, but round holes seem to be preferredto accomplish the object of the invention, namely,

and

to combine full cushioning action and maximum I heat transfer.

The rubber envelope I! may be a thin rubber without fabric backing, but a combination of a thinfabric and rubber is preferred. It may be secured, or adhesively secured, at theedges, depending upon the desire of the manufacturer tiie type of rubber material used. Preferably, employ a thin rubber-fabric material and close it by a double stitching operation. Because of the insulating character of the layers II, the rubber envelope l2 may,if desired, be dispensed with in favor of a simple type of fabric bag, but the advantages of the rubber envelope are sumciently marked that I prefer to use it.

'The outer envelope may be of plain weave, and formed as shown to permit ready removal ffo'r' laundering, the cushioning eil'ect of the layers- I I being adequate for all practical purposes. As

shown, however, it includesa cloth base 2|, with sections 22 of piling'spaced from each other. This piling, as indicated, is attached to the cloth base in such a manner that its individual threads are perpendicular to the cloth base. As a con sequence of this construction, surprisingly enough, there is very little resistance to the passage of heat, the effect being almost the same as if only the cloth base 2| were present. The piling, however, provides greater cushioning effect than would beprovided by a heavily woven cloth of comparable thickness, which cloth would have a pronounced heat insulating eflfect. 'As a conse-, quence of the cushioning action'of the outer envelope I, it may be used without the-layers H, where the full cushioning action obtained by the conjoint use of both is not desired. I regard this feature as an important, though limited, aspect of my invention.

Ifhe preferred embodiment of my invention, as

shown in the drawings, may be modified in various ways. In general, most of the modifications embodying the concepts of the present invention are clear from the preceding descriptionv or are obvious to the skilled manufacturer. It may be noted, however, that the thin rubber envelope may be left out of the combination, or it may be substituted by a textile envelope. The sponge rubber layers'may be housed within the outside envelopeand on the outside of the thin rubber envelope. The thin rubber sheeting comprising the envelope may be vulcanized onto the rubber layers, and the assembly then vulcanized at the three edges or, ,altematively, the holes I8 may extend only partway through the sponge rubber layer, leaving -a thin, imperi'orate outer layer as the equivalent of the thin rubber envelope.

I have explained my invention in det in order that those skilled in the art may un erstand and practice it, but the claims are to be takenas definitive of its scope.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. In a ,heating pad, a sheet-like support for a heating element, a heating element, as a resistance wire, secured to said sheet-like support,

' a sponge rubber pad on at least one side of said heating element, and an outer imperforate covering for said sheet-like support and pad, said sponge rubber pad provided with perforations sufllcient in total area to permit a substantial proportion of the heat from said heating element readily to pass therethrough, but insumcient to permit breakdown of the essential structure of said pad under pressure, whereby not tov impair appreciably its cushioning function.

. '2. In a heating pad, a heating element member of general sheet-like character, sponge rubber layers on opposite sides thereof, and an imperforate rubber bag member enclosing the heating element member and sponge rubber layers, said sponge rubber layers provided with a plurality of substantially regularly arranged perforations, the total area of all of said perforations comprising from one-third to one-half of the-area of one surface through which they extend.

3. In a heating pad, a sheet-like support member, resistance wire secured thereto to form a heating element, a thermostat secured to said support member and connected to said resistance wire to limit-the temperature of said wire in response to the passage of electric current therethrough, an imperforate rubber envelope enclosing the whole, and an outer envelope of textile material enclosing said rubber envelope, said textile material comprising a relatively thin cloth base, and a plurality of regularly arranged spaced sections of piling substantially vertical to said cloth base, whereby said piling provides a cushioning action without limiting appreciably the passage of heat through the textile material as a whole.

4. In a heating pad, a sheet-like support member, resistance wire secured thereto to form a heating element, a thermostat secured to said support member'and connected to said resist-- ance wire to limit the. temperature of said wire in response to the passage of electric current therethrough, an imperforate rubber envelope enclosing the whole, and an outer envelope of textile material enclosing said rubber envelope, said textile material comprising a relatively thincloth base, and a plurality of parallel spaced plane of said cloth, whereby said ridges of piling provide a cushioning action'without limiting appreciably the passage oi! heat through the textile material as a whole.

5. The combination defined in claim 4', wherein said envelope of textile material is 'releasably closed along one edge thereof, whereby to permit ready removal thereof for laundering or exchange tor a similar envelope.

6. The combination in a heating pad. of the type employing an electric heating and control means, including electric resistance wires and 1311811110.

layers of aerated elastic rubber-like material hav-" ing a plur'ality of perforations therein, thetotal area of which is-from about one-third to onehalf of the area of said layers, an imperiorate rubber envelope enclosing the same, and an outer envelope oi textile material enclosing said rubber envelope, said textile material comprising a relativelythin cloth base, and aplurality'ot-regularly arranged spaced sections 0! piling substantially vertical tm said cloth base, whereby saidpiling provides a cushioning action without limiting appreciably the passage of heat through the textile material as awhole;

7. The combination in a heating .pad '01 the type employing an electric heating and control means, including electric resistance wires and thermostats secured to av sheet-like base, of a pair of layers of aerated elastic rubber-like material having a plurality oiperforations therein, the total area oi which-is from about one-third to one-half of the ,area'of said layers, and an outer envelope oi textile material, said textile material comprising a relatively thin cloth? base, and a plurality of regularly arranged spaced sections oi piling substantially vertical to said-cloth base-whereby said piling provides a cushioning action without limiting appreciably thepassage of heat through the textile material as a whole.

8. ma heating pad. a sheet-like support mem ber, resistance wire secured thereto, thermostatic" control means associated with said wire to limit the delivery of electric current thereto in response .to predetermined temperature, a'layer of per-' rotated sponge rubber on opposite sides, of said pre ously described members, and 'an outer. en-' support member 'to enclose the -sarne, 'and cushion said resistance wire and thermostat means, an imperiorate rubber .envelopeenclo'sing all of said vel ottextilematerial enclosing said rubber envelope, wherein the perforations of'each sponge rubber layer are regularly arranged, and their total: area comprises. from about one-third to one-half of the total area'oi the layers, whereby not more than ten to fli'teen percent or the heat is-absorbed by'said layers, and; the cushioning action thereof is substantially uni pa red.

9. In a heating pad, a sheet-like support mem- "ber, resistance wire secured thereto to form a heating element a thermostat secured to said support member and connected to said resistance another and outer envelope of textile material enclosing said first-mentioned envelope, said texstats secured to a sheet-like base, of a pair 0! tile material comprising a relatively thin cloth j base, and a plurality of regularly-arranged spaced ioning action without limiting appreciably'the passageot heat through the textile material as .a whole; i

I 10. In a heating pad,asheet-, like support inember,-resistancewire secured thereto tolform a. heating element, a thermostat'securedto said support member and connected to said resist-,

'ance'wire to limit the temperature of said wire j in response to the passage of electric current therethrough, an envelope enclosing the whole. and another and outer envelope or textile'ma-- cloth base, and a plurality of, parallel spaced terial enclosing said first-mentioned envelope, said textile material comprising a relatively thin ridges of piling, the piling oi'said ridges composed of fibers disposed substantially vertical to the plane of said cloth, whereby'said ridges-oi piling provides cushioning action without limiting appreciably the passage oi heat throughthe textile material as a-whole.

11. The combination in a'heating pad oi the type employing an electricheating and control means, including electric resistance wires and thermostats secured to a sheet-like base, oi a pair 0! layers of aerated elastic rubber-like materialhaving a plurality of perforations therein, the total. area of which is from about one-third to one-half oi! the area of said layers, an envelope enclosing the same; and another and outer envelope oi textile: material enclosing said first mentioned envelope, said textile material comprising a relatively thin cloth base,.and a plurality of regularly arranged spaced sections 01' piling.-

substantially vertical to said cloth base, whereby said pilin'g provides a cushioning action without limiting appreciably the passage of heat through the-textile material as a whole.

I rLMe'cLEARY, 

